you are right, I haven't thought about stuff like this (*) :( Probably because I don't have such things in my code - for that reason, strings can stay the same... But you already showed me, that this problem is not as trivial as I thought :(

Even if you don't do this in *your* code, you are very likely include modules which you haven't written by yourself (for example, Perl standard modules, and you likely can't say for sure that they don't do such tricks.

that was because, we working in seperated teams, and also using own 'team-modules' - know we had a functionality which was interesting for another team and we want give them the code to do this particular thing without giving them all our modules...

In this case, it would make more sense IMO to put the functionality you want to give to other team members, in a separate module. This has also the advantage that instead of few big modules, you get many small ones.